Extended bracketing control

Shooting exposure bracketed gets more and more important for panorama creation, but most cameras still only support three brackets at 2EV steps maximum. But there are possibilities to work around this limitation. Many solutions support not only bracketing control but eventually many other features (timelaps, sound or light trigger etc). However, exposure bracketing is the main interest here.

This page is about how to extend the camera capabilities. If you look for general HDR information start at the HDR page.

PTP bracketing

Picture Transfer Protocol (PTP) is built into many cameras and should provide a means of not only transferring pictures over USB but also controlling the camera remotely. PTP is part of the WIA architecture on Windows, hence it is fairly easy to build a camera control software using f.e. Visual Basic. For other OS's the gphoto project should provide access to such cameras.

Hence there are many programs to control your camera from a computer but only few that do the same from a portable device. However, availability of cheap USB host circuitry has triggered some do-it-yourself projects and apparently even some smartphones can use USB hosts nowadays.

Supported cameras

Not all PTP enabled cameras implement all features. Hence it's impossible to tell which cameras can be used for PTP bracketing. The most complete list of cameras supporting PTP or other means of direct control is found in the gphoto project. If your camera is listed, there is a chance that one or the other software will support it. But it is still better to look on the vendor or developer page.

iOS + OSX

DSLR camera remote A smartphone app and a program running on a PC connected to the camera.

Bulb mode bracketing

A much cheaper way to control a camera shutter is using bulb mode and opening and closing the shutter directly by cable or infrared. Unfortunately no short exposure times are possible since for fast times the second shutter curtain starts to close already while the first one is still not fully open. Hence bulb mode bracketing is limited to times slower than 1/120s to 1/4s depending on the camera, with fastest possible times getting unreliable. Great for night time HDR but nothing for daylight use where fast speeds are needed. There are lot's of DIY projects and many smartphone apps in this category.

Supported cameras

Any camera that has a cable or infrared release and that supports bulb mode should work.

Commercial

The PClix intervalometer has the feature of a programmable shutter push length (to 99/100th sec) and programmable bulb length which can be combined with interval timing -- which makes it useful for continuous sequences of autobracketed bursts.

Do-it-yourself

DIY bulb mode bracketing should be safe if you don't apply power to the connector.

Camera software hacks

In-camera bracketing limits are mostly artificial. Where the camera software can be extended or replaced better functionality can be retrofitted. However, there is a small risk of malfunction or even permanent damage to your camera.

CHDK The Canon Hack Development Kit extends the firmware of Canon powershot cameras by many useful features among which is extended exposure bracketing. Also read the FAQ Can CHDK damage your camera?

MagicLantern A firmware hack for some Canon DSLRs providing not only bracketing but mainly extended video functionality. Also read the FAQ "Is it safe?"

Other possibilities

Another idea of doc-diy is to butcher a battery grip and emulate the dial wheel by a micro controller. This way exposure could be controlled simply and directly.